itunes is your friend here. its kinda like the windows media player for OS X but better. you can view movies in itunes and have the playlist there to. itunes now allows you to view movies in the itunes window without another window popping up which i like. then you can just press esc to go back to the playlist and then double click on the movie again to see where you just left off. itunes used to be terrible at playing movies a few versions ago but i guess they've polished off the quicktime frameworks and it plays movies fine now.
as for playing different formats in itunes just get perian and flip4mac. quicktime/itunes will now be able to play pretty much everything xvid, divx, wmv, ac3 etc. but iTunes will only play movies with file extensions it understands. so if you just save for example an avi movie as a reference file or a self-contained movie (this one has a bigger file size) with quicktime pro and import it into itunes, itunes will play it fine.
if you dont like playing video in itunes then just use quicktime. i use vlc as a last resort. i dont like it that much... got an ugly interface and it seems to crash a lot for me.
also a tip for importing movies into itunes. if you dont want itunes to orgainse your movies into its own special folder and you want to keep them somewhere else then just untick "copy items to itunes music folder when adding to library" then your itunes library size wont grow at a huge rate.
this is what i do and works perfect for me.